Method to restore hydrophobicity in dielectric films and materials

ABSTRACT

Silica dielectric films, whether nanoporous foamed silica dielectrics or nonporous silica dielectrics are readily damaged by fabrication methods and reagents that reduce or remove hydrophobic properties from the dielectric surface. The invention provides for methods of imparting hydrophobic properties to such damaged silica dielectric films present on a substrate. The invention also provides plasma-based methods for imparting hydrophobicity to both new and damaged silica dielectric films. Semiconductor devices prepared by the inventive processes are also provided.

FIELD OF THE INVENTION

The invention provides methods and compositions for restoringhydrophobicity to the surfaces of silica dielectric films. These filmsare used as insulating materials in the manufacture of semiconductordevices such as integrated circuits (“ICs”) in order to ensure low andstable dielectric properties in these films.

BACKGROUND OF THE INVENTION

As feature sizes in integrated circuits approach 0.25 μm and below,problems with interconnect RC delay, power consumption and signalcross-talk have become increasingly difficult to resolve. It is believedthat the integration of low dielectric constant materials for interleveldielectric (ILD) and intermetal dielectric (IMD) applications will helpto solve these problems. While there have been previous efforts to applylow dielectric constant materials to integrated circuits, there remainsa longstanding need in the art for further improvements in processingmethods and in the optimization of both the dielectric and mechanicalproperties of such materials used in the manufacture of integratedcircuits.

Silica Dielectric Films

One material with a low dielectric constant is silica. In particular,silica can be applied as a foamed dielectric material. For the lowestpossible dielectric values, air is introduced into silica dielectricmaterials. Air has a dielectric constant of 1, and when air isintroduced into a silica dielectric material in the form of nanoporousor nanometer-scale voids or pore structures, relatively low dielectricconstants (“k”) are achieved.

Nanoporous silica is attractive because it employs similar precursors,including organic-substituted silanes, e.g., tetramethoxysilane (“TMOS”)and/or tetraethoxysilane (“TEOS”), as are used for the currentlyemployed spin-on-glasses (“SOG”) and chemical vapor disposition (“CVD”)silica SiO₂.

Nanoporous silica films have previously been fabricated by a number ofmethods. Simply by way of example, suitable silicon-based precursorcompositions and methods for forming nanoporous silica dielectric filmsby solvent removal, are described, for example, by the followingco-owned U.S. patent applications Ser. No. 09/054,262, filed on Apr. 3,1998, Ser. No. 09/111,083, filed on Jul. 7, 1998, 60/098,068, filed onAug. 27, 1998, 60/098,515, filed on Aug. 31, 1998, Ser. No. 09/044,831,filed Mar. 20, 1998, Ser. No. 09/044,798, filed Mar. 20, 1998, and Ser.No. 09/328,648, filed on Jun. 9, 1999, all incorporated herein byreference herein.

Broadly, a precursor in the form of, e.g., a spin-on-glass compositionthat includes one or more removable solvents, is applied to a substrate,and then polymerized and subjected to solvent removal in such a way asto form a dielectric film comprising nanometer-scale voids.

When forming such nanoporous films, e.g., wherein the precursor isapplied to a substrate by spin-coating, the film coating is typicallycatalyzed with an acid or base catalyst and water to causepolymerization/gelation (“aging”) during an initial heating step. Thefilm is then cured, e.g., by subjecting the film to one or more highertemperature heating steps to, inter alia, remove any remaining solventand complete the polymerization process, as needed. Other curing methodsinclude subjecting the film to radiant energy, e.g., ultraviolet,electron beam, microwave energy, and the like.

Co-owned application Ser. Nos. 09/291,510 and 09/291,511, both filed onApr. 14, 1999, incorporated by reference herein, provide silicon-basedprecursor compositions and methods for forming nanoporous silicadielectric films by degrading or vaporizing one or more polymers oroligomers present in the precursor composition. Co-owned applicationSer. No. 09/566,287, filed on May 5, 2000, provides silicon-basedprecursor compositions and methods for forming nanoporous silicadielectric films by degrading or vaporizing one or more compounds orpolymers present in the precursor composition. U.S. Pat. No. 5,895,263describes forming a nanoporous silica dielectric film on a substrate,e.g., a wafer, by applying a composition comprising decomposable polymerand organic polysilica i.e., including condensed or polymerized siliconpolymer, heating the composition to further condense the polysilica, anddecomposing the decomposable polymer to form a porous dielectric layer.

Processes for application of precursor to a substrate, aging, curing,planarization, and rendering the film(s) hydrophobic are described, forexample, by co-owned U.S. Ser. No. 09/392,413, filed on Sep. 9, 1999,Ser. No. 09/054,262, filed on Apr. 3, 1998, and Ser. No. 09/140,855,filed on Aug. 27, 1998, among others.

Semiconductor Manufacturing Processes Remove Hydrophobic Groups

Undesirable properties result when the silica-based materials, such asthe nanoporous silica dielectric films mentioned herein, form nanoporousfilms with surfaces, including surfaces of the pore structures, thatcontain silanol groups. Silanols, and the water that they can adsorbfrom the air are highly polarizable in an electric field, and thus willraise the dielectric constant of the film.

To make nanoporous films substantially free of silanols and water, oneof two strategies is employed.

-   -   (A). In one method, an organic reagent, i.e., a surface        modification agent, such as hexamethyldisilazane or        methyltriacetoxysilane, is optionally introduced into the pores        of the film to add organic, hydrophobic capping groups, e.g.,        trimethylsilyl groups.    -   (B) Films are produced from precursor compositions comprising        starting reagents or precursors that advantageously produce        hydrophobic silica dielectric films without further processing.

These processes are described, e.g., by co-owned U.S. Ser. No.09/378,705, filed on Aug. 23, 1999, Ser. No. 09/140,855, filed on Aug.27, 1998, Ser. Nos. 09/234,609 and 09/235,186, both filed on Jan. 21,1999, the disclosures of which are incorporated by reference herein.

Etching and Plasma Remove Hydrophobic Functional Groups

Damage to nanoprous silica dielectric films during during semiconductormanufacturing processes results from the application of aggressiveplasmas and/or etching reagents to etch trenches and vias intodielectric films. Plasmas are also used to remove photoresist filmsduring fabrication of semiconductor devices (hereinafter referred togenerally as intergrated circuits or “ICs”. The plasmas used aretypically composed of the elements oxygen, fluorine, hydrogen ornitrogen (in the form of free atoms, ions and/or radicals).

Dielectric films which are exposed to these plasmas during trench, via,etch and/or photorcsist removal are easily degraded or damaged. Porousdielectric films have a very high surface area and are thereforeparticularly vulnerable to plasmas damage. In particular, silica baseddielectric films which have organic content (such as methyl groupsbonded to Si atoms) are readily degraded by oxygen plasmas. The organicgroup is oxidized into C0₂ and a silanol or Si—OH group remains on thedielectric surface where the organic group formerly resided. Poroussilica films depend on such organic groups (on pore surfaces) to remainhydrophobic. Loss of the hydrophobicity makes the dielectric constantrise (the low dielectric constant of such films is the key desiredproperty of such materials).

Wet chemical treatments are also used in IC production for the purposeof removing residues leftover after trench or via etching. The chemicalsused are often so aggressive they will attack and remove organic groupsin silica based dielectric films, especially porous silica films. Again,this damage will cause the films to lose their hydrophobicity. Wetchemical etchants include, for example, amides, such asN-methylpyrrolidinone, dimethylformamide, dimethylacetamide,; alcoholssuch as ethanol and 2-propanol; alcoholamines such as ethanolamine;amines such as triethylamine; diamines such as ethylenediamine andN,N-diethylethylenediamine; triamines such as diethylenetriamine,diamine acids such as ethylenediaminetetracetic acid “EDTA”; organicacids such as acetic acid and formic acid; the ammonium salts of organicacids such as tetramethylammonium acetate; inorganic acids such assulfuric acid, phosphoric acid, hydrofluoric acid; fluoride salts suchas ammonium fluoride; and bases such as ammonium hydroxide andtetramethyl ammonium hydroxide; and hydroxl amine; commercialformulations developed for post etch wet cleaning such as EKC 505, 525,450, 265, 270, and 630 (EKC Corp., Hayward Calif.), and ACT-CMI andACT-690 (Ashland Chemical, Hayward, Calif.). to name but a few art-knownetchants.

There is also a need for a more rapid and efficient method of ensuringthat newly produced silica dielectric films are hydrophobic to startwith. Heretofore, as noted above, all such methods have employed liquidor vapor phase surface modification agents. No report of plasma phasesurface modification agents and/or methods

SUMMARY OF THE INVENTION

In order to solve the above mentioned problems and to provide otherimprovements, the invention provides nanoporous silica dielectric filmswith a low dielectric constant (“k”), e.g., typically ranging from about1.5 to about 3.8, as well as novel new methods of producing thesedielectric films. Broadly, the invention provides methods of impartinghydrophobic properties to silica dielectric film(s) present on asubstrate during the process of fabricating a semiconductor or ICdevice. As exemplified hereinbelow, the film is preferably formed from amethylhydridosiloxane precursor, although any other art-knownsilicon—based precursor, such as any commercial spin on glass (SOG), isreadily employed.

Typically the damage to the silica dielectric film is produced bycontact with at least one etchant or ashing reagent in such a way as tosubstantially damage or remove previously existing film hydrophobicity.Art-known etchants employed in IC fabrication include, for example,compositions that include one or more of the following types of agents:amides such as N-methylpyrrolidinone, dimethylformamide,dimethylacetamide; alcohols such as ethanol, 2-propanol; alcoholaminessuch as ethanolamine, and ethylenediamine; amines such as triethylamine;diamines such as N,N-diethylethylenediamine, triamines such asdiethylenetriamine, amine—acids such as ethylenediaminetetracetic acid;organic acids such as acetic acid and formic acid; the ammonium salts oforganic acids such as tetramethylammonium acetate; inorganic acids suchas sulfuric acid, phosphoric acid, hydrofluoric acid; fluoride saltssuch as ammonium fluoride; and bases such as ammonium hydroxide andtetramethyl ammonium hydroxide; and hydroxl amine; commericalformulations developed for post etch wet cleaning such as EKC 505, 525,450, 265, 270, and 630 (EKC Corp., Hayward Calif.), and ACT-CMI andACT-690 (Ashland Chemical, Hayward, Calif.), and combinations thereof.Ashing agents include oxygen-derived plasmas, and the like.

The methods of the invention include, without limitation, the steps of(a) contacting the damaged silica dielectric film with a surfacemodification composition at a concentration and for a time periodeffective to render the silica dielectric film hydrophobic; and (b)removing unreacted surface modification composition, reaction productsand mixtures thereof. The surface modification composition includes atleast one surface modification agent, i.e., a compound or chargedderivative thereof, suitable for removing silanol moieties from thedamaged silica dielectric film.

Optionally, the etchant-damaged nanoporous silica dielectric film issubjected to wet cleaning prior to step (a).

In one embodiment, the surface modification composition includes atleast one compound having a formula as follows:R₃SiNHSiR₃, RxSiCly, RxSi(OH)y R₃SiOSiR₃, RxSi(OR)y, MpSi(OH)[4-p],RxSi(OCOCH₃)y and combinations thereof,wherein x is an integer ranging from 1 to 3,

-   -   y is an integer ranging from 1 to 3 such that y=4-x,    -   p is an integer ranging from 2 to 3;    -   each R is an independently selected from hydrogen and a        hydrophobic organic moiety;    -   each M is an independently selected hydrophobic organic moiety;        and    -   R and M can be the same or different.

In another particular embodiment, the surface modification compositionincludes at least one of the following agents or compounds:acetoxytrimethylsilane, acetoxysilane, diacetoxydimethylsilane,methyltriacetoxysilane, phenyltriacetoxysilane, diphenyldiacetoxysilane,methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane,methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane,methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorsilane,methylsilane, dimethylsilane, trimethylsilane, hexamethyldisilazane,2-trimethylsiloxypent-2-ene-4-one, n-(trimethylsilyl)acetamide,2-(trimethylsilyl)acetic acid, n-(trimethylsilyl)imidazole,trimethylsilylpropiolate, trimethylsilyl(trimethylsiloxy)-acetate,nonamethyltrisilazane, hexamethyldisiloxane, trimethylsilanol,triethylsilanol, triphenylsilanol, t-butyldimethylsilanol,diphenylsilanediol, trimethoxysilane, triethoxysilane, trichlorosilane,and combinations thereof. As exemplified hereinbelow, the surfacemodification agent is the compound methyltriacetoxysilane.

Advantageously, the methods of the invention are readily applied tosilica dielectric film that is either a nanoporous silica dielectricfilm, other foamed silica dielectric, or simply a nonporous silicadielectric. In a still further embodiment, the surface modificationcomposition optionally includes a solvent. Suitable solvents include,for example, ketones, ethers, esters, hydrocarbons, and combinationsthereof.

The surface modification composition is contacted with the damagedsilica dielectric film as a liquid, vapor or gas, and/or plasma. If inthe form of a plasma, the plasma can be derived from a silane compound,a hydrocarbon, an aldehyde, an ester, an ether, and/or combinationsthereof.

It is also contemplated that the methods of the invention includemethods of imparting hydrophobic properties to a silica dielectric filmpresent on a substrate, whether a newly applied film or one damaged byfabrication processes or reagents. The method includes the steps of: (a)contacting the silica dielectric film with a plasma comprising at leastone surface modification agent, at a concentration, and for a timeperiod, effective to render the silica dielectric film hydrophobic; and(b) removing unreacted surface modification composition, reactionproducts and mixtures thereof, wherein the surface modificationcomposition comprises at least one surface modification agent suitablefor removing silanol moieties from the damaged silica dielectric film.

Semiconductor or IC devices manufactured using the above-describedmethods and reagents are also provided.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates a cross-section schematic of a nanoporous silicadielectric film on a silicon nitride layer, with a photoresist patter(left) and the topology resulting from the etching process (right).

FIG. 1B illustrates a cross-section schematic of a nanoporous silicadielectric film on a silicon nitride layer, with a copper conductorpattern and Ta barrier (right).

FIG. 1C illustrates the same pattern as for 1B, after chemicalmechanical polishing.

FIG. 2 illustrates the top surface of the wafer produced by Example 10.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly, as noted in the Background discussion, supra, certainreagents and methods have been described by co-owned, copending patentapplications, for use in enhancing the pore surface hydrophobicity ofnanoporous silica dielectric films during or immediately after filmformation. It has now been unexpectedly found that certain surfacemodification reagents are useful for solving a newly appreciatedproblem, that of reversing damage to nanoporous silica dielectric filmsformed as part of a semiconductor device by subsequent manufacturingsteps and reagents.

In order to better appreciate the scope of the invention, it should beunderstood that unless the “SiO₂” functional group is specificallymentioned when the term “silica” is employed, the term “silica” as usedherein, for example, with reference to nanoporous dielectric films, isintended to refer to dielectric films prepared by the inventive methodsfrom an organic or inorganic glass base material, e.g., any suitablestarting material containing one or more silicon-based dielectricprecursors. It should also be understood that the use of singular termsherein is not intended to be so limited, but, where appropriate, alsoencompasses the plural, e.g., exemplary processes of the invention maybe described as applying to and producing a “film” but it is intendedthat multiple films can be produced by the described, exemplified andclaimed processes, as desired. The term, “film” as used herein withregard to silica dielectric materials is intended to encompass any othersuitable form or shape in which such silica dielectric materials areoptionally employed.

Additionally, the term “aging” refers to the gelling or polymerization,of the combined silica-based precursor composition on the substrateafter deposition, induced, e.g., by exposure to water and/or an acid orbase catalyst. Gelling is optionally applied to precursors selected toform foamed, i.e., nanoporous dielectric films, and/or nonporousdielectric films. Gelling can be accomplished by the above-describedcrosslinking and/or evaporation of a solvent.

The term “curing” refers to the hardening and drying of the film, aftergelling, typically by the application of heat, although any otherart-known form of curing may be employed, e.g., by the application ofenergy in the form of an electron beam, ultraviolet radiation, and thelike.

The terms, “agent” or “agents” herein should be considered to besynonymous with the terms, “reagent” or “reagents,” unless otherwiseindicated.

A. Methods for Preparing Dielectric Films

Dielectric films, e.g., interlevel dielectric coatings, are preparedfrom suitable precursors applied to a substrate by any art-known method,including spin-coating, dip coating, brushing, rolling, spraying and/orby chemical vapor deposition. The precursor can be an organic polymerprecursor, a silicon-based precursor and/or combinations thereof. Thecoating is then processed to achieve the desired type and consistency ofdielectric coating, wherein the processing steps are selected to beappropriate for the selected precursor and the desired final product.

Typically, silicon-based dielectric films, including nanoporous silicadielectric films, are prepared from a suitable silicon-based dielectricprecursor, e.g., a spin-on-glass (“S.O.G.”) material blended with one ormore solvents and/or other components. Prior to application of the basematerials to form the dielectric film, the substrate surface isoptionally prepared for coating by standard, art-known cleaning methods.

After the precursor is applied to the substrate surface, the coatedsurface is optionally contacted with a planarization object, i.e., inthe form of a compression tool, for a time and at a pressure effectiveto transfer any desired pattern to the dielectric coating or film on thesubstrate surface, as described in detail in co-owned Ser. No.09/549,659, filed Apr. 14, 2000, incorporated by reference herein.

B. Surface Modification Methods and Reagents

Reagents

A suitable surface modification composition includes one or more surfacemodification agents able to remove silanol groups from the surface of asilica dielectric film that it is desired to render hydrophobic. Forexample, a surface modification agent is a compound having a formulaselected from the group consisting of Formulas I (1-8)

(1) R₃SiNHSiR₃, (2) R_(x)SiCl_(y), (3) R_(x)Si(OH)_(y), (4) R₃SiOSiR₃,(5) R_(x)Si(OR)_(y), (6) M_(p)Si(OH)_([4-p]), (7) R_(x)Si(OCOCH₃)_(y),(8) R_(x)SiH_(y)

and combinations thereof.

Further, x is an integer ranging from 1 to 3, y is an integer rangingfrom 1 to 3 such that y=4-x, p is an integer ranging from 2 to 3; each Ris an independently selected from hydrogen and a hydrophobic organicmoiety; each M is an independently selected hydrophobic organic moiety;and R and M can be the same or different. The R and M groups arepreferably independently selected from the group of organic moietiesconsisting of alkyl, aryl and combinations thereof.

The alkyl moiety is substituted or unsubstituted and is selected fromthe group consisting of straight alkyl, branched alkyl, cyclic alkyl andcombinations thereof, and wherein said alkyl moiety ranges in size fromC₁ to about C₁₈. The aryl moiety is substituted or unsubstituted andranges in size from C₅ to about C₁₈. Preferably the surface modificationagent is an acetoxysilane, or, for example, a monomer compound such asacetoxytrimethylsilane, acetoxysilane, diacetoxydimethylsilane,methyltriacetoxysilane, phenyltriacetoxysilane, diphenyldiacetoxysilane,methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane,methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane,methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorsilane,methylsilane, dimethylsilane, trimethylsilane, hexamethyldisilazane,2-trimethylsiloxypent-2-ene-4-one, n-(trimethylsilyl)acetamide,2-(trimethylsilyl)acetic acid, n-(trimethylsilyl)imidazole,trimethylsilylpropiolate, trimethylsilyl(trimethylsiloxy)-acetate,nonamethyltrisilazane,, hexamethyldisiloxane, trimethylsilanol,triethylsilanol, triphenylsilanol, t-butyldimethylsilanol,diphenylsilanediol, trimethoxysilane, triethoxysilane, trichlorosilane,and combinations thereof. As exemplified hereinbelow, one preferredsurface modification agent is methyltriacetoxysilane.

Additional surface modification agents include multifunctional surfacemodification agents as described in detail in co-owned U.S. Ser. No.09/235,186, incorporated by reference herein, as described above. Suchmultifunctional surface modification agents can be applied in eithervapor or liquid form, optionally with or without co-solvents. Suitableco-solvents include, e.g., ketones, such as acetone, diisolpropylketone,2-heptanone, 3-pentanone, and others, as described in detail in co-ownedU.S. Ser. No. 09/111,084, filed on Jul. 7, 1998, the disclosure of whichis incorporated by reference herein. For example, as described in detailin U.S. Ser. No. 09/235,186, as incorporated by reference above, certainpreferred surface modification agents will have two or more functionalgroups and react with surface silanol functional groups while minimizingmass present outside the structural framework of the film, and include,e.g., suitable silanols such asR₁Si(OR₂)₃   Formula IIwherein R₁ and R₂ are independently selected moieties, such as H and/oran organic moiety such as an alkyl, aryl or derivatives of these. WhenR₁ or R₂ is an alkyl, the alkyl moiety is optionally substituted orunsubstituted, and may be straight, branched or cyclic, and preferablyranges in size from C₁ to about C₁₈, or greater, and more preferablyfrom C₁ to about C₈. When R₁ or R₂ is aryl, the aryl moiety preferablyconsists of a single aromatic ring that is optionally substituted orunsubstituted, and ranges in size from C₅ to about C₁₈, or greater, andmore preferably from C₅ to about C₈. In a further option, the arylmoiety is not a heteroaryl.

Thus, R₁ or R₂ are independently selected from H, methyl, ethyl, propyl,phenyl, and/or derivatives thereof, provided that at least one of R₁ orR₂ is organic. In one embodiment, both R₁ and R₂ are methyl, and atri-functional surface modification agent according to Formula V ismethyltrimethoxysilane.

In another embodiment, a suitable silane according to the invention hasthe general formula ofR₁Si(NR₂R₃)₃   Formula IIIwherein R₁, R₂, R₃ are independently H, alkyl and/or aryl. When any ofR₁, R₂, R₃ are alkyl and/or aryl, they are defined as for R₁ and R₂ ofFormula II, above. In preferred embodiments, R₁ is selected from H, CH₃,C₆H₅, and R₂ and R₃ are both CH₃. Thus tri-functional surfacemodification agents according to Formula III include, e.g.,tris(dimethylamino)methylsilane, tris(dimethylamino)phenylsilane, and/ortris(dimethylamino)silane.

In yet another embodiment, a suitable silane according to the inventionhas the general formula ofR₁Si(ON═CR₂R₃)₃   Formula IVwherein R₁, R₂, R₃ are independently H, alkyl and/or aryl. When any ofR₁, R₂, R₃ are alkyl and/or aryl, they are defined as for Formula II,above. In one preferred embodiment, R₁ and R₂ are both CH₃, and R₃ isCH₂CH₃. Thus tri-functional surface modification agents according toFormula IV include, e.g., methyltris(methylethylkeoxime)silane.

In yet a further embodiment, a suitable silane according to theinvention has the general formula ofR₁SiCl₃   Formula Vwherein R₁ is H, alkyl or aryl. When R₁ is alkyl and/or aryl, they aredefined as for Formula II, above. In one preferred embodiment, R₁ isCH₃. Thus tri-functional surface modification agents according toFormula V include, e.g., methyltrichlorosilane.

In a more preferred embodiment, the capping reagent includes one or moreorganoacetoxysilanes which have the following general formula,(R₁)_(x)Si(OCOR₂)_(y)   Formula VI

Preferably, x is an integer ranging in value from 1 to 2, and x and ycan be the same or different and y is an integer ranging from about 2 toabout 3, or greater.

Useful organoacetoxysilanes, including multifunctionalalkylacetoxysilane and/or arylacetoxysilane compounds, include, simplyby way of example and without limitation, methyltriacetoxysilane(“MTAS”), dimethyldiacetoxysilane (DMDAS), phenyltriacetoxysilane anddiphenyldiacetoxysilane and combinations thereof.

Methods

Optionally, the surface modification agent or agents are mixed with asuitable solvent such as 2-heptanone, applied to the nanoporous silicasurface in the form of a vapor or liquid, and then dried.

In an alternative embodiment, surface modification is provided byexposing the etchant-damaged silica dielectric film to a plasma which isderived from any of the above mentioned surface modification reagents.In a typical procedure, the dielectric film is placed in a plasmagenerating chamber, such as a plasma enhanced chemical vapor deposition(PECVD) system; the vapor of a surface modification reagent and argonvapor are passed through the plasma generating chamber; then an RFenergy source is activated to create a plasma; the argon gas is includedto help promote the formation of plasma. The plasma is composed of ionicfragments derived from the surface modification reagent; for example,the ion fragment CH₃Si⁺ is generated from methylsilane (CH₃SiH₃). Thisfragment reacts with silanol groups to form hydrophobic Si—CH₃ moities.Any of the above mentioned surface modification reagents can be used forthis plasma induced surface treatment. The most preferred silane reagentis methylsilane.

Other suitable surface modification reagents for a plasma inducedsurface modification treatment include C₁-C₁₂ alkyl and aromatichydrocarbons. The most preferred hydrocarbon is methane. Other reagentsfor plasma induced surface modification include aldehydes, esters, acidchlorides, and ethers. Suitable aldehydes include acetaldehyde andbenzaldehyde; suitable esters include ethylacetate and methyl benzoate;suitable acid chlorides include acetyl chloride and benzyl chloride; andsuitable ethers include diethyl ether and anisole. A wide variety ofsingle wafer or multiple wafer (batch) plasma systems can be used forthis process; these systems include so called downstream ashers, such asthe Gasonics L3510 photoresist asher, PECVD dielectric depositionsystems such as the Applied Materials P5000, or reactive ion etch(“RIE”) systems.

Broadly, the conditions for the plasma process are within the followingranges: chamber temperature, 20C to 450° C.; RF power, 50 W to 1000 W;chamber pressure, 0.05 to 100 torr; plasma treatment time, 5 seconds to5 minutes; and surface modification flow rate, 100-2000 sccm; inert gasflow rate (typically argon), 100-2000 sccm.

The artisan will appreciate that the invention is also contemplated toencompass methods of imparting a hydrophobic surface to silicadielectric films, porous and/or nonporous, whether damaged or not, byapplication of the above-described plasma surface treatments.Semiconductor devices or ICs manufactured using these methods are also apart of the present invention.

EXAMPLES

Thickness and Refractive Index of Films: In the following examples,ellipsometry was also used to determined the thickness and refractiveindex (RI) of the produced film.

Dielectric Constant of Films: In the following examples, the dielectricconstant (k) was determined from a measurement of the capacitance of ametal-insulator-metal (MIM) structure at 20C. The MIM structure isformed by sputtering aluminum onto the film, which is coated on a lowresistivity Si wafer (0.25 ohms-cm) through a circular dot mask. Anappropriately biased voltage was applied to the MIM structure, and thecapacitance (C) across the structure was then measured at 1 MHz. Thearea (A) of the aluminum dot was measured by lightmicroscope-micrometry. The thickness (Th) of the film near the aluminumdot was measured by ellipsometry. The k value is then calculated from:k=(C*Th)/ε*Awherein ε is the permittivity of free space (8.86*10⁻¹⁴ F/cm).

Example 1 Formation of Nanoporous Silica Film Treated with MTAS

A nanoporous silica precursor was synthesized as described by co-ownedU.S. Ser. No. 09/235,186, filed on Jan. 22, 1999, incorporated byreference herein. Thus, the precursor was prepared by adding 208 mL oftetraethoxysilane, 94 mL of triethyleneglycol monomethylether(TriEGMME), 16.8 mL deionized water, and 0.68 mL of IN nitric acidtogether in a round bottom flask. The solution was allowed to mixvigorously and heated (heating and stirring were begun at the same time)to about 80° C. and refluxed for 1.5 hours, to form a clear solution.The resulting solution was allowed to cool down to room temperature andthen it was diluted 25% by weight with ethanol, and filtered through a0.1 micron Teflon® filter.

About 2 mL of the nanoporous silica precursor was deposited onto a 4″silicon wafer and then spun at 2500 rpm for 30 seconds. Then the filmwas gelled/aged in a vacuum chamber using the following conditions:

-   -   1. The chamber was evacuated to 250 torr.    -   2. 15M ammonium hydroxide was heated and equilibrated at 45° C.        and introduced into the chamber to increase the pressure to 660        torr for 4 minutes.    -   3. The chamber was refilled with air and the film was removed        from the chamber for surface treatment/solvent exchange.

The surface treatment/solvent exchange of the film was carried out usingthe following conditions:

-   -   1. The reagent used for the surface modification was prepared by        mixing 5 grams of methyltriacetoxysilane, “MTAS”, (Gelest,        Tullytown, Pa. 19007) with 95 grams of 3-pentanone to form a        clear colorless solution.    -   2. The aged film was put on the spinning chuck and spun at 250        rpm.    -   3. About 30 mL of the above MTAS solution was spun on the film        without allowing the film to dry for 20 seconds.    -   4. Then the film was spun dry at 2500 rpm for 10 second and then        the film was removed from the chuck and subjected to heat        treatment, as follows.

The film obtained from the above process was then heated at 175 and 320°C., under air, for 60 seconds for each step, respectively. Then it wascured in a furnace at 400° C. for 30 minute under nitrogen. Testing offilm properties was conducted as described supra, and the measuredphysical properties are reported in Example 9, below.

Example 2 Formation of Non-Porous Methylhydridosiloxane Film

A precursor composition was prepared as described by U.S. patentapplication Ser. No. 09/044,798, filed on Mar. 20, 1998, the disclosureof which is incorporated by reference herein. Thus, a one liter jacketedreactor equipped with a nitrogen inlet, dry ice condenser and amechanical stirrer was charged with 1000 mL hexanes, 80 mL ethanol, 25mL water and 61.3 g Amberjet 4200 catalyst (Rohn & Haas Co.). Themixture was equilibrated for 0.5 hr with stirring at 25° C. (circulatingbath). A mixture of trichlorosilane (14.3 mL, 0.142 Mol) andmethyltrichlorosilane (66.7 mL, 0.568 Mol) was added to the reactorusing a peristaltic pump over a period of 35 minutes. Upon completion ofthe silane addition, hexane was pumped through the lines for 10 minutes.The reaction was stirred for 23 hours, then filtered through a Whatman#4 filter. The filtered solution was placed in a separatory funnel andthe water/ethanol layer removed. The remaining hexane solution was driedover 4 Å molecular sieves (170 g) for 5 h and then filtered through a 1mm filter. The hexanes were removed using a rotary evaporator to give awhite solid product (23.1 g), 52% yield. The GPC of this product,referenced to polystyrene standards gave a Mw of 11,885 with apolydispersity of 6.5.

The above precursor was used to form a nanoporous dielectric silica filmon a substrate as described by U.S. patent application Ser. No.09/227498, filed on Jan. 7, 1999, the disclosure of which isincorporated by reference herein. Thus, methyl isobutyl ketone (MIBK)(63.5 g) was dried over 4 Å molecular sieves and combined with 14 g ofthe non-porous methylhydridosiloxane. The solution was filtered to 0.2mm. The solution was coated on a bare 4 inch silicon wafer using aconventional spin coater. Approximately 3 ml of the polymer solution wasplaced on the wafer. After a 3 second delay, the wafer was spun at 2000rpm for 20 seconds. The coated wafer was baked on three successive hotplates for one minute each at 150° C., 200° C., and 350° C.,respectively. The baked wafer was then cured in a nitrogen atmosphere ina horizontal furnace set initially at 300° C., followed by a ramp to380° C. at a rate of 4° C./minute, where it was held for 10 minutes,then increased to 400° C. at a rate of 1° C./minute. The furnacetemperature was held at 400° C. for one hour and then lowered back to300° C. over a period of about 2 hours. The properties of the completedfilm (before ashing treatment, see example 9) were as follows: ThicknessRI k C—H Abs. Si—H Abs. Before Ashing 4020 Å 1.362 2.5 0.20 0.05

Example 3 Photoresist Ashing

The wafer coated with nanoporous silica in Example 1 is placed withinthe chamber of a TEL 85 DRM L3510 etcher. Pure oxygen is made to flowthrough the chamber at less than 500 sccm. The wafer temperature is 25°C. An RF plasma source is activated at a power consumption level of 500W for a period of 1 minute. During this 1 minute period the film isexposed to a plasma derived from oxygen. The total pressure during thisprocess is less than 500 millitorr. The predicted film properties beforeand after this ashing treatment are: TABLE 2 Thickness RI k C—H Abs.Before 7050 Å 1.165 2.2 0.15 After 6960 1.160 3.8 0.02

Fourier transform infrared (“FTIR”) spectroscopy confirms that the O—Habsorption curve is increased in amplitude at about 3500 cm⁻¹ in filmssubjected to the ashing treatment, relative to untreated (non-ashed)films. This confirms that the ashing treatment removes most of the C—Hbonds attributable to the methyl groups in the original film. It haspreviously been confirmed (see, for example, co-owned U.S. Ser. No.09/235,186, incorporated by reference, supra)that the relative amplitudeof the O—H absorption peak is predictive of the relative k values of theresulting film(s), all other parameters being equal.

Example 4 Wet Cleaning

The nanoporous silica coated wafer processed through the ashingtreatment in Example 3 is immersed in a wet cleaning solution (EKC 630,a proprietary post-etch wet cleaning solution from EKC Corp, Hayward,Calif.)) for 20 minutes at a temperature of 70° C. The wafer is thenimmersed in 2-propanol for 30 seconds, and then immersed in water for 30seconds. Finally, the wafer was heated on successive hot plates set at175 and 320° C. (1 minute each plate). The film properties before andafter this wet cleaning treatment are shown below in Table 3. TABLE 3Thickness RI k C—H Abs. Before 6960 Å 1.160 3.8 0.02 After 7015 1.1727.9 0.00 After 425° C. + 6930 1.159 4.1 0.00 1 hr After 425° C. + 70351.167 6.4 0.00 1 d

The film has absorbed more water as indicated by the higher k value andhigher refractive index after the wet cleaning treatment/IPA/water/175°C./320° C. process. The wafer was then heated at 425° C. in a furnace(nitrogen atmosphere) for 30 minutes. The k was 4.1 one hour after the425° C. treatment. The film absorbed water during the one day followingthe 425° C. heating step as indicated by the increase of k to 6.4.

Example 5 Restoring Hydrophobicity and Low K using MTAS Solution

A nanoporous silica film is produced according to Example 1, and thesame film is treated with the ashing process of Example 3 and the thenwet cleaning process of Example 4 (not including the 425° C. furnacetreatment). The wafer coated with this film is immersed in a solutioncomposed of methyltriacetoxysilane (MTAS), 15% wt/wt, and 2-heptanone,85% wt/wt.; the temperature of the solution is 20° C.; the duration ofimmersion is 10 minutes. The wafer is removed from the MTAS containingsolution, and then it is placed on a spin coater. To remove reaction byproducts and unreacted MTAS, the wafer is spun at 3000 rpm for 1 minutewhile pure 2-heptanone is dispensed onto the center of the wafer. Atotal of 30 ml of 2-heptanone is dispensed during this 1 minute spin. Toremove residual 2-heptanone, the wafer is heated successively on hotplates at 175C for 1 minute, and then at 320C for 1 minute (both in anair atmosphere). The predicted properties of the film are shown below inTable 4, as follows. TABLE 4 Thickness RI k C—H Abs. Before Ash & 7085 Å1.165 2.2 0.16 Cleaning After Ash & 6960 Å 1.159 9.1 0.00 Cleaning AfterMTAS 7015 1.169 2.2 0.15

Restoration of the low dielectric constant is achieved by this MTASsolution treatment performed after the ash and wet clean steps. The MTASsolution treatment returns methyl content into the film as indicaed bythe FTIR C-H absorption, and the film is hydrophobic as indicated by thevery low O—H absorption. The k is once again 2.2.

Example 6 Restoring Hydrophobicity and Low k using MTAS Vapor

A nanoporous silica film is produced according to Example 1, and thesame film is treated with the ashing process of Example 3 and the wetcleaning process of Example 4 (not including the 425° C. furnacetreatment). The wafer coated with this film is placed inside acylindrical chamber made of aluminum (225 mm inside diameter, 30 mminside height). The chamber is contained inside a chemical fume hood.There is a synthetic rubber gasket between the top edge of the chamberand the chamber lid. The chamber is heated by use of electrical heatingtape bonded to the outer chamber surfaces and to the lid. There are fourstainless steel (¼ inch inside diameter) tubes connected to the reactionchamber; and each tube has a stainless steel valve. One tube isconnected to a vacuum pump; another is connected to the MTAS reservoir;and the third tube serves as a vent line; the fourth tube connects to avacuum gauge. The MTAS reservoir is a stainless steel, 1 liter volume,cylinder. The latter contains about 100 g of MTAS; the outer surface ofthe MTAS reservoir is heated to 70° C. using heating tape. The chamberis also heated to about 70° C. The chamber is evacuated to about 1 torrand then the valve to the vacuum pump is closed. Next, the valve to theMTAS reservoir is opened so the MTAS vapor enters the chamber. Afterfive minutes, the MTAS chamber valve is closed and the vacuum valve isopened. After 1 minute, the vacuum valve is closed and the vent valve isopened to let air into the chamber. The wafer is then removed andanalyzed, and the predicted properties of the films are shown below inTable 5. TABLE 5 Thickness RI k C—H Abs. Before Ash & 7025 Å 1.167 2.20.17 Cleaning After Ash & 6990 1.159 7.5 0.00 Cleaning After MTAS 70601.170 2.3 0.17 VaporThe MTAS vapor treatment returns methyl content into the film asindicated by the FTIR C—H absorption, and the film is hydrophobic asindicated by the very low FTIR O—H absorption. The dielectric constantis also now very low again.

Example 7 Restoring Hydrophobicity & Low k using Carbon-Based Plasma

A nanoporous silica film is produced according to Example 1, and thesame film is treated with the ashing process of Example 3 and the wetcleaning process of Example 4 (not including the 425° C. furnacetreatment). The wafer coated with this film is placed inside a GasonicsL3510 photoresist asher. The asher chamber is evacuated to 200 mtorr andmethane (CH₄) gas is allowed to flow through the chamber at thispressure. The methane flow rate is 500 sccm. The asher is maintained atabout 20° C. Then the RF source of the chamber is activated; the powersetting is 100 W, and the RF frequency is 13.56 MHz. After 2 minutes,the RF source is deactivated, and the methane gas flow is reduced tozero. The asher chamber is then vented with air, and the wafer isremoved for analysis of the film. Table 6, below, shows the predictedproperties of the films. TABLE 6 Thickness RI k C—H Abs. Before Ash &7135 Å 1.163 2.2 0.17 Cleaning After Ash & 7045 1.158 10.3 0.00 CleaningAfter C-Based 7090 1.174 2.2 0.20 Plasma

The carbon based plasma treatment re-incorporates organic content intothe film as indicated by the C-H FTIR absorption. The low k property andhydrophobicity are also restored; the FTIR shows a very small O—Habsorption.

Example 8 Restoring Hydrophobicity and Low k using Silane Based Plasma

A nanoporous silica film is produced according to Example 1, and thesame film is treated with the ashing process of Example 3 and the wetcleaning process of Example 4 (not including the 425° C. furnacetreatment). The wafer coated with this film is placed inside a plasmaenhanced chemical vapor deposition chamber (PECVD), Applied MaterialsP5000. Methylsilane (CH₃SiH₃) is used as the reagent for creating ahydrophobic pore surface. Argon gas is used to promote the creation of aplasma. The RF plasma source is activated for a period of 20 seconds.The conditions employed during this period are detailed in Table 7, asfollows. TABLE 7 RF power: 700 W CH3SiH3 flow rate: 500 sccm Argon flowrate: 1200 sccm Chuck temperature: 400° C. Chamber pressure: 10 torr

The wafer is removed from the chamber and then analyzed, and thepredicted properties of the films are provided by Table 8, below. TABLE8 Thickness RI k C—H Abs. Before Ash & 7010 Å 1.160 2.1 0.13 CleaningAfter Ash & 6930 1.158 6.9 0.00 Cleaning After Silane 7090 1.170 2.20.18 Plasma

After the silane plasma treatment the film is hydrophobic as indicatedby the low k value and the very low O—H absorption in the FTIR spectrum.The C—H absorption in the FTIR shows that organic content has been addedto the film.

Example 9 Restoring Hydrophobicity and Low K for Non-PorousSilsesquioxane Using MTAS Solution

A silsesquioxane film is formed on a wafer as in Example 2. This filmcoated wafer is processed through photoresist ashing and wet cleaningtreatments as in Examples 3 and 4. The film coated wafer is then exposedto an MTAS solution to restore its hydrophobicity and low k properties;The procedure for MTAS solution treatment of Example 5 is used. Theproperties of the film before and after these treatments are shown byTable 9, below. TABLE 9 Thickness RI k C—H Abs. Si—H Abs. Before Ashing   4020 Å 1.362 2.5 0.20 0.05 After Ashing 3650 1.410 3.2 0.10 0.025After wet cleaning 3650 1.410 3.2 0.10 0.025 After 400° C./1 hr 36001.390 3.0 0.1 0.025 After MTAS treatment 3690 1.37 2.6 0.15 0.025

Restoration of the low dielectric constant is achieved by this MTASsolution treatment performed after the ash and wet clean steps. The FTIRspectrum exhibits an O—H absorption after the ash and wet cleantreatment, and reduced C—H and Si—H absorptions; the k is also higher.After the MTAS treatment the k value is 2.6, very close to the originalvalue before ashing; the C—H absorption is also higher, which indicatesthat methyl groups from MTAS have been added to the film; and the filmis hydrophobic again as indicated by the absence of a O—H absorption.

Example 10 Fabrication of Damascene Trench Structure Using NanoporousSilica

This example illustrates the application of the inventive process tofabrication of a damascene trench structure incorporating a nanoporoussilica dielectric material.

The example is described with reference to FIGS. 1A, 1B and C. A 200 mmSi wafer is oxidized by art known methods to form an SiO₂ layer (5000 Å)on the top surface of the wafer. The wafer is then coated with a layer(10) of PECVD silicon nitride, SiN, (1000 Å). Next, a layer ofnanoporous silica (20) (7000 Å) is coated on the same wafer according tothe procedure in Example 1 (the entire process through and including the400° C. furnace step). Another layer (30) of PECVD silicon nitride (500Å) is then deposited on the nanoporous silica layer. A photoresistcoating or pattern (40) is then applied to this stack of dielectriclayers, and the photoresist is processed in the customary manner to forma pattern of lines and spaces (50).

An anisotropic etching process is then performed to create the trenches(60), that are 0.13 microns in width. The etching is performed in aplasma etching chamber, in which CF₄ is the primary etch gas, and inwhich there is a sufficient bias voltage to cause anisotropic (downward)etching. The photoresist layer is removed by oxygen based plasmatreatment (“ashing” as in Example 3) to create the structure of (70) inFIG. 1B. It is in this ashing step that the nanoporous silica ischemically altered; the oxygen plasma species remove the methyl groupsfrom the pore surfaces by oxidation reactions; the resulting poresurfaces become hydrophilic. A wet cleaning process is also performedafter the ashing step (as in Example 4).

Next, a Tantalum (Ta) barrier liner film (250 Å) (80) is deposited intothe trenches and over the top SiN layer; this deposition is performedusing the physical vapor deposition (sputtering) technique. A Cu “seedlayer”, not shown, is deposited by sputtering Cu onto the Ta layer. Thenthe trenches are filled with electroplated Cu (90). In the final step,the excess Cu and the Ta liner on top of the SiN layer are removed bychemical mechanical polishing to form the structure of FIG. 1C, showingthe copper lines (100) and the nanoporous silica dielectric (20).

A view of the top surface of the wafers in FIG. 2 shows that the inlaidCu contains the pattern shown in FIG. 1C; the dimensions depicted inthis drawing are not proportional to the actual structure. There are twolarge square probe pads (110) (each 100 micron×100 micron). Each probepad is connected to a “comb” of parallel lines (120); the width of eachline is 0.13 μm.

The two combs are “interdigitated” such that a line from one comb is inbetween and parallel to two of the lines from the other comb. The linesare 1000 μm long. There are 101 lines in each comb (for simplicity only7 lines are shown in the figure); There are 200 parallel capacitors inthis interdigitated comb structure (2*(101-1)=200). The dielectricconstant (k) for the nanoporous silica residing between the Cu lines iscalculated by the following equation for a parallel plate capacitor:C=k*ε*A/d

-   -   C=capacitance    -   68 =permittivity of free space=8.86×10⁻¹⁴ F/cm    -   A=area of each parallel plate=height×length=0.7 μm×1000 μm=700        μm²=7×10⁻⁶ cm²    -   d=distance between the plates=0.13 μm=1.3×10⁻⁵ cm

To calculate k from a measured capacitance value, the above equation isrearranged to:k=(C/200)*d/(ε*A)

Given the very large area of the parallel lines, the effects thesubstrate and the probe pads on the measured capacitance are ignored inthe calculation of k. The capacitance is divided by 200 because thereare 200 parallel plate capacitors in the interdigitated comb structure.The total capacitance in the comb structure is measured by connectingthe probe pads to a capacitance meter and then applying a voltage acrossthe two pads. Table 10, below, shows predicted results of capacitancemeasurements for structures shown in FIGS. 1C and 2, which are treatedwith MTAS solution for hydrophobicity (see Example 5, supra) after thewet photoresist ashing and cleaning steps. Predicted values forstructures not treated with MTAS solution are also shown. TABLE 10Predicted Capacitance Process (Farads) Calculated k With MTAS solution24 × 10⁻¹² 2.5 treatment Without MTAS solution 60 × 10⁻¹² 6.3 treatment

The data shows that the predicted interline capacitance and thecalculated k are almost 3 times greater for the structure which does notreceive the MTAS solution treatment following the ashing and wet cleansteps. A structure treated with MTAS is predicted to have a k value of2.5 for the nanoporous silica and SiN dielectric composite. This k valueis slightly higher than the k value (2.2) of the unpatterned nanoporousfilm made in Example 1. In the present example, the measured capacitanceis affected by both the thick nanoporous silica 7000 Å film and the thin500 Å silicon nitride film, both of which reside between the Cu lines.The approximate k value for PECVD SiN is about 7.0. Thus, the dilectricconstant of the composite dielectric stack (nanoporous silica and SiN)is slightly higher than 2.2.

1-16. (canceled)
 17. A method of imparting hydrophobic properties to asilica dielectric film present on a substrate, the method comprising (a)contacting a silica dielectric film with a plasma comprising at leastone surface modification composition, at a concentration, and for a timeperiod, effective to render the silica dielectric film hydrophobic; and(b) removing unreacted surface modification composition, reactionproducts and mixtures thereof, wherein the surface modificationcomposition comprises at least one surface modification agent suitablefor removing silanol moieties from the silica dielectric film.
 18. Themethod of claim 17 wherein a plasma derived from a silane compound isused as the surface modification composition.
 19. The method of claim 17wherein the surface modification composition is a plasma derived from acompound selected from the group consisting of a hydrocarbon, analdehyde, an ester, an ether, and combinations thereof.
 20. Asemiconductor device produced by a process comprising: (a) forming ahydrophobic silica dielectric film on a substrate that is patterned withfeatures and suitable for the manufacture of a semiconductor device, (b)contacting said silica dielectric film and features with an etchant orashing reagent in such a way as to substantially damage or removepreviously existing hydrophobicity of said dielectric film; (c) treatingsaid damaged silica dielectric film by contacting the damaged silicadielectric film with a surface modification composition at aconcentration and for a time period effective to render the silicadielectric film hydrophobic; and removing unreacted surface modificationcomposition reaction, products and mixtures thereof wherein the surfacemodification composition comprises at least one surface modificationagent suitable for removing silanol moieties from the damaged silicadielectric film; wherein steps (a) and (b) are conducted in any order,and step (c) is conducted after step (b), and wherein step (c) isrepeated after each step (b).
 21. The semiconductor device of claim 20produced by a process wherein a wet cleaning step is conducted aftereach step (b) and before each step (c).
 22. A semiconductor deviceproduced by a process comprising: (a) contacting a silica dielectricfilm with a plasma comprising at least one surface modification agent,at a concentration, and for a time period, effective to render thesilica dielectric film hydrophobic; and (b) removing unreacted surfacemodification composition, reaction products and mixtures thereof,wherein the surface modification composition comprises at least onesurface modification agent suitable for removing silanol moieties fromthe silica dielectric film.
 23. The method of claim 17 wherein thesurface modification composition comprises at least one compound havinga formula selected from the group consisting of: R₃SiNHSiR₃, RxSiCly,RxSi(OH)y R₃SiOSiR₃, RxSi(OR)y, MpSi(OH)[4-p], RxSi(OCOCH₃)y andcombinations thereof, wherein x is an integer ranging from 1 to 3, y isan integer ranging from 1 to 3 such that y=4-x, p is an integer rangingfrom 2 to 3; each R is an independently selected from hydrogen and ahydrophobic organic moiety; each M is an independently selectedhydrophobic organic moiety; and R and M can be the same or different.24. The method of claim 17 wherein the surface modification compositioncomprises at least a compound selected from the group consisting of,acetoxytrimethylsilane, acetoxysilane, diacetoxydimethylsilane,methyltriacetoxysilane, phenyltriacetoxysilane, diphenyldiacetoxysilane,methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane,methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane,methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorsilane,methylsilane, dimethylsilane, trimethylsilane, hexamethyldisilazane,2-trimethylsiloxypent-2-ene-4-one, n-(trimethylsilyl)acetamide,2-(trimethylsilyl) acetic acid, n-(trimethylsilyl)imidazole,trimethylsilylpropiolate, trimethylsilyl(trimethylsiloxy)-acetate,nonamethyltrisilazane, hexamethyldisiloxane, trimethylsilanol,triethylsilanol, triphenylsilanol, t-butyldimethylsilanol,diphenylsilanediol, trimethoxysilane, triethoxysilane, trichlorosilane,and combinations thereof.
 25. The method of claim 17 wherein the silicadielectric film is either nanoporous or non-porous.
 26. The method ofclaim 17 wherein the silica dielectric film is a methylhydridosiloxanefilm.
 27. The method of claim 17 wherein the surface modificationcomposition comprises methyltriacetoxysilane.
 28. The method of claim 17wherein the surface modification composition comprises a solventselected from the group consisting of ketones, ethers, esters,hydrocarbons, and combinations thereof.
 29. The method of claim 17wherein a plasma derived from a silane compound is used as the surfacemodification composition.
 30. The method of claim 14 wherein the surfacemodification composition is a plasma derived from a compound selectedfrom the group consisting of a hydrocarbon, an aldehyde, an ester, anether, and combinations thereof.
 31. The semiconductor device of claim20 wherein the etchant is a plasma comprising atoms, ions and/orradicals selected from the group consisting of oxygen, fluorine,hydrogen, nitrogen and combinations thereof.
 32. The semiconductordevice of claim 20 wherein the etchant is a wet etchant that comprisesat least one agent selected from the group consisting of: an amide, analcohol, an alcoholamine, an amine, a triamine, an acid, a base andcombinations thereof.
 33. The semiconductor device of claim 32 whereinthe amide is selected from the group consisting ofN-methylpyrrolidinone, dimethylformamide, dimethylacetamide andcombinations thereof.
 34. The semiconductor device of claim 32 whereinthe alcohol is selected from the group consisting of ethanol, 2-propanoland combinations thereof.
 35. The semiconductor device of claim 32wherein the etchant comprises at least one agent selected from the groupconsisting of ethanolamine, ethylenediamine, triethylamine,N,N-diethylethylenediamine, diethylenetriamine, amine.ethylenediaminetetracetic acid; organic, acetic acid, formic acid,tetramethylammonium acetate, sulfuric acid, phosphoric acid,hydrofluoric acid; ammonium fluoride, ammonium hydroxide, tetramethylammonium hydroxide, hydroxl amine and combinations thereof, providedthat the combinations are of agents that do not neutralize one another.36. The semiconductor device of claim 20 wherein the surfacemodification composition is contacted with the damaged silica dielectricfilm in a state selected from the group consisting of liquid, vapor orgas, and plasma.